Telephone-exchange maintenance system



June 11, 1929.

c. v. TAPL|N Erm. 1,717,074

TELEPHONE EXCHANGE MAINTENANCE SYSTEM 2 Sheets-Sheet Filed Aug. 22, 1927 Arm/ver Patented June 11, 1929.

UNITED STATES PATENT OFFICE.

NEW JERSEY, LOUIS M. ALLEN, OF NEW YORK, N. Y., AND ARNOLD S. BERTELS, OF TENAFLY, NEW JERSEY; SAID TAPLIN ASSIGNOR TO THE AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPO- RATION OF NEW YORK, AND SAID ALLEN AND BERTELS ASSIGNORS T0 BELL TELEPHONE LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORA- TION 0F NEYV YORK.

TELEPHONE-EXCHANGE MAINTENANCE SYSTEM.

Application led August 22, 1927.

The present invention relates to maintenance systems in an automatic telephone exchange. More specifically, it relates to a maintenance system for automatic switches in one ollice connected over two conductor trunks to a distant office;

In multi-oilice automatic telephone areas interconnect-ions are ellected between olices over trunk conductors. Ordinarily, two con` ductor trunks are used for such interconnections. In accomplishing such an interconnection, t-he manipulation ot' the apparatus at a subscribers station causes the auton'iatically operable appara-tus in one ol'lice to select terminals connected to a trunk which extends to a second automatic telephone ollice. Associated with the terminals connected to the two conductors of each trunk is a third terminal used for test- )urposes. It is, of course, necessary in ma {ing' a .selection of a trunk to test its condition in order to determine whether it is busy or idle. The busy or idle condition is determined by testing' this third terminal. This terminal is not connected by a conductor to a distant ollice. The selection ot' switches located in a distant oliicc is therefore made at the originating ollice and is controlled by vthe condition placed upon the test terminal in the originating oliice.

'.lests oi selector switches connected to two conductor trunks are ordinarily made from the originating' otlice. A busy condition may thus be associated with the test terminal duringv the test of the switch at the distant ottico. Further, the condition of the selector s vitch to be tested must be determined before it is seif/.ed for test. An arrangement oi this kind for selecting and testing selector switches is shown in Patent No. 1,573,412 issued to H. lV. MacDougall et al. February lo, 1926. The automatically operable testing equipment as shown in the aforementioned patent, is located in the otlice in which the trunks originate in order to test selector switches over the two conductor trunks lo cated in distant o'flices. Diliiculties are encountered with this method of testing, for example, when a fault is encountered in the Serial No. 214,520.

selector switch under test it is necessary for the testing operator to notify a maintenance man in the distant oi'lice. rlhe invention has for its object a more desirable arrangement for testing selector switches connected to two conductor trunks, wherein the testing equipment is located in the same oHice with the selector switches to be tested. This method of testing has not heretofore been used because oi the dilliculty in marking the trunk busy at the ollice in which the trunk-originates.

In accordance with the present invention one auxiliary selector' switch, the same as the selector switches connected to the two conductor trunks, is used as a substitute selector switch for a selector switch under test. A relay is associated with each two conductor trunk in the same ollice with the selector' switches connected to the trunks. This relay is operable for disconnectingthe trunk conductors from an associated selector switch and connectingr the trunk conductors to the auxiliary selector switch. The auxiliary selector switch is provided for response to an incoming,r call over the trunk during` the period of time that the selector switch, normally associated with this trunk, is being tested. The auxiliary selector switch under this condition performs the normal function of completing telephone connections to subscribers stations.

Having set an automatically operable test-ing` device for the selection of switches, the condition of each switch to be tested is determined by the testing' equipment before seizure. In order to do this, a conductor is extended from the testing device to each selector switch in the oilice to be tested. The busy or idle condition of the selector switch is thus determined at the switch instead of at the originating otlice. When it found that the selector switch associated with the testing circuit is idle the aforementioned relay isoperated for disassociating' the trunk from the selector switch to be tested and associating the trunk with the auxiliary selector switch. Then the test ot a selector switch is completed and the switch Cil restored to normal, the condition of the auxiliary switch is determined before it is disconnected from the trunk. This is accomplished with automatically operable apparatus in order that the auxiliary switch remain associated with a busy trunk until the trunk is released by the termination of a telephone conversation. In order to determine the condition of the auxiliary selector switch, a conductor is extended from the auxiliary switch to the testing apparatus. The selection and testing of selector switches is t-hus accomplished without reducing the number of swit-ches available for telephone connections, and without limiting the selection of trunks or lines connected to said switches.

The figures of the drawing have been organized to illustrate an interconnection between two subscribers stations M and N. Fig. 1 illustrates subscribers station M connected to a district and sender in a machine switching otlice. The district is shown associated with an o'liice trunk selector and a selected trunk is shown extending to a second machine switching office. Figs. 2, 3,-l^, 1B and 5 illustrate the apparatus of this sec ond machine switching oliice. Fig. 2 comprises a trunk relay for replacing a service selector or switch, Fig. 1l^ with the auxiliary selector switch Fig. -lB and for associating the service selector switch with the testing equipment. Jacks are also shown connected to the conductors extending to this relay for connecting the testing circuit with any individual trunk. The apparatus shown in F ig'. 2 is individual to each trunk extended from the first to the second oliice. Fig. tl is a diagramnnitic illustration of an auto` mat-ically operable or manually operable test-- ing circ-uit. This testing circuit may be of the type disclosed in Patent No. 1,573,412 issued to H. lV. MacDougall et al. February 16, 1926, or of the type disclosed in Patent No. 1,617,405 issued to H. XV. MacDougall February 15, 1927.

Fig. 1^ illustrates a selector switch of the t-ype used for a iirst selector in a machine switching otlice and operable over trunk conductors incoming from a distant machine switching oliice. Fig. 4B is a duplicate of Fig. 4^ and is therefore not shown in detail. Fig. 1^ illustrates one of a large plurality of like selectors operable for service telephone connections. Fig. 4B may be used to replace any one of the plurality of service selectors.

Fig. 5 illustrates diagi'ammatically a iinal selector and subscribers station N. The circuits diagrammatically illustrated in Figs. 1 and 5 are described in detail in Y Patent 1,501,871 issued to F. A. Stearn July 15, 1924. It is therefore believed that further detailed explanation should not be required in this description.

The apparatus shown in the drawing is well-known in the art. It may be stated,

.however.. that the switch for associatinrr the for selectin@ the switches to be tested. he

L s: contacts of switch are ass rated directly with the selectors to be tested whereas in the aforementioned patent the connectors are associated with testing selccton: for selecting the switches to be tested. T o start an automatic routine test of the sclector switches Fig. 4^, key 124 is actuated. An Venergizing circuit is thus established "i the operation of magnet 110 to rotate brush assembly from position 0 to position 1 in which position it has been shown in the drawing. This circuit may be traced from ground through the left inner contact of rclay 123, right Contact of hey 1211, brush and its associated contact in position 0, conf tact and winding of switch magnet 110 to battery. A test of the condition of tl e sel i: tor switch of Fig. 4^ is now made 'to a.. tain whether it is idle or busy. If the switch of Fig. Ll^ is connected in service a ground is associated with conductor 1&0 either through the contact of rtl y 200 er through the lei'tlower contact of cam The selector switch of Fig. 4^ is -zlescril detail in the aforenientioned Patent no. 1,501,871 to F. A. Stearn. The description of Fig. 4 of this patent will be found to accurately agree with Fig. 4^ with the citception of the left contact of relay 200 and the left lower contact of cam 221. 1t will he not-cd in the description of Fig. -1 of the aforementioned patent that relay,r 200 operates immediately upon the seizure of the switch for a service T connection. the ground shown connected to the leit contact of relay 200 has been used to indicate the busy condition of the switch to the tei-cinc device until such time as the sequence i has rotated in the position V1%. Tinl tion of the sequence switch eslablis a permanent busy ground to indicate the con dition of the switch to the testine' device until the switch has been restored to its normal position. lVhen the testing device is associated with a busy switch the aforemeu tioned ground is connected to the winding` of relay 121, which operates. it will he noted that a circuit is established by the asfill lill) sociation of brush 113 with terminal 1 tor energizing relays 10() and 120. Because oi the large number of springs associated with relays and 120 they are slower to operate than relay 121. The operatienot' relay 121, from ground connected by a busy switch to conductor 149, opens the operating circuit for relays 100 and 120. The operation et relay 100 at this time would disassociat i the trunk conductors from a busy selector switch. Under this condition relay 121 remains opera-ted until the switch Fig. 4^ is restored. Relay 121 is then released to prrmitthe operation of relays 100 and 12d.

Letit be assumed that the selector switch Fig. 4^ is in its normal position and therefore a ground is not associated with ceuductor 149. Upon the association of brush 111 with conductor 149 a circuit is not e'ta lished to operate rela-y 121. The cento. i ot this relay remains normal and a circuit is established to operate relays 100 and 121).V This circuit may be traced from hattthrough the winding of relay 1007 brush and its associated Contact, winding of renaY 120, normal contact o'l relay 121. to ground through the left inner contact et rela]Y 12'v2 The operation of relay 100 ass(iciates` conductors 140 and 141 with cemluctors and 145 which are extended to the auxil selector switch Fig. 4B. It the trant; i resented by conductors 140 and 141 is new seized for service the telephone connection will be completed by the auxiliary selector switch Fig. 4B and the nal selector' switch Fig. 5. The operation of relay 100 'lui-ther associates testing circuitconducters 146 and 147 with conductors 142 and 143 extending to the selector switch to be tested. Tl eration of relay completes the in"l nection of the testing circuit with the Weetor switch Fig. 4^. The operation or rel 120 ope-ns the circuit for relay 121 at right outer contact. A circuit is est through the right inner Contact et rel l2v) for energizing sequence switch mag et 130.

This circuit may be traced from ground through this right inner contact ol relay 120. lett contact of key 124, lower contact of cam 131, winding 13() to battery. The sequence switch is thus driven from position 1 t sition 2 in which position testing condiL are associated with conductors 160 and 161. A progressive test of the selector switch Fig. 4^ is now made as described in the aforementioned Patent No. 1,573,412. Upon e c pletion of each one of the progressive te: ground is associated with conductor 162 by the movement of testing circuit apparatus in order to reposition 'the sequence switch which extends to the apparatus of the auxiliary switch Fig. 4B. Conductor 148 is connected to apparatus of the auxiliary switch in the same manner as shown for conductor 149. If the auxiliary selector switch has been seized for service during the period ol time that the selector switch 4^ is under test a ground is connected to conductor 148. This ground therefore completes a connection for the operation of relay 122 when the sequence switch 130 arrives in position 16. The sequence switch 130 may continue to rotate into position 18 but is prevented from moving out of position 18 by t-he operation of relay 122. The energizing circuitfor magnet 130 in position 18 is held open at the right contact of relay 122. The sequence switch is thus held in position 18 until the auxiliary switch 4I3 is released and returned to its normal position. This is done in order to prevent interference with service connections during the test of selector switches. lVhen the auxiliary switch is restored to normal the ground is removed from conductor 148 causing the release ol relay 122. The release of relay 122 establishes an energizing circuit through its right contact tor sequence switch magnet 130. The sequence switch now rotates from position 18 to position 1. During the rotation of the sequence switch through position 18% a circuit is established to energize and release switch magnet 110 through the contact ot' cam 133. The brushes of switch 110 are thus rotated one position for associating' a different trunk and selector switch with the testing circuit.

The progressive testing of thel selector switches throughout the entire telephone oflice may be accoinplished in the manner clescribed without reducing the number of selectable switches or trunks.

It may be desirable at times to test a particular one of the selector switches Fig. 4^. For this purpose jacks 126 and 128 are associated with each trunk relay. Plugs and 127 may be inserted in jacks 126 and 128. For such a test key 125 is operated in order that switch 11() will remain in its normal postion zero. The key 124 is operated and allowed to remain operated until the sequence switch 130 has rotated out of position 1. Key 124 then released to preventthe sequence switch from again moving out of position 1 when the test of the selector switch has been completed. The testing apparatus operates in the same manner for the test o1 a particular selector switch as here described for progressive tests in which the switch 110 is used.

.t will be noted that the springs of relay 100 are arranged so that conductors 144 and are associated with conductors 140 and 141 before conductors 140 and 141 are disassociated from conductors 142 and 143.

The purpose of this spring arrangement is to prevent the possibility ot t-ransmitting a false pulse to a sender that has at that moment seized the trunk conductors 140 and 141. A momentary time interval elapses between the seizure ot the trunk and the operation etl relay 200 in the selector switch. It during this time inteival the loop circuit between the selector switch and the sender were allowed to be opened a false pulse wo-uld be registered in the sender. The registration ol2 this false pulse would cause the auxiliary selector switch to be positioned upon the wrong terminals. A taulty connection would be the result ot this incorrect recording ot pulses.

It at any time it is desirable to restore switch 110 to its normal position trom an intermediate testing position key 129 is operated. rthis key may be operated at any time during the test ot a selector switch. l/V hen the test of the selector switch is completed and the sequence switch 130 rotates from position 18, a circuit is est-ablished in position 181/2 to operate relay 123. This circuit may be traced from ground through the contact of key 129, right lower and upper contacts of cam 13G to battery through the winding of relay 123, A locking circuit for relay 123 is established through its right contact, lett upper and lower contact-s of cam 136 to ground through key 129. The operation of relay 123 disconnects ground from the operating circuit for the sequence switch magnet 130. The sequence switch therefore remains in position 1 and the relay 123 remains locked until the key 129 is restored. Ground is also removed from the operating circuit for magnet 110 so that it will remain in its normal position when restored. Ground is also removed from the opei'ating circuit for relays 120 and 100. rl`he operating circuit -for relay 121 is opened at the lett outer Contact of relay 123. The operation of relay 123 further establishes an energizing circuit for switch magnet 110 from batterythrough the winding and contact of magnet 110, brush 116 and its associated contacts to ground through the left inner contact et relay 123. The switch 110 is thus restored to its normal position. During the restoration kot this switch the conductors extending between the various trunk relays and the testing circuit apparatus are held open in order that no interference with operating circuits will be encountered. After switch 110 is restored to normal the start key 12-1 is released previous to t-he release ot key 129.

Key 124C is permitted to remain in its operated position after key 129 is operated in order to prevent interference with service if the sequence .switch 130 is in position 1. TheV release of key 129 causes the release of relay 1231er restoring the circuit to its normal condition.

lt is not the intention to limit the use ot this invention to the testing of appara-tus connected to a distant point by a two-conductor trunk. rlhe invention may be used for the inspection or test ot any apparatus where it is desirable to maintain unrestricted selection et said apparatus.

What is claimed is:

1. In a system tor inspecting a plurality ej select-able apparatus, an automatically operable combination oi devices including an apparatus 'for successively seizing said selectable apparatus for inspection and Yfor rearranging the apparatus so that the number ol apparatus available tor selection is unchanged by said seizures.

2. in a system tor inspecting a plurality ot selectable switches7 an autoniatically operable combination ot devices including a switch tor successively seizing' said selectable switches for inspection and tor rearranging the switches so that the number ot switches available for selection is unchanged by said seizures.

3. ln a system for inspecting a plurality et selectors7 an automatically operable device :tor progressively seizing` said apparatus for inspection and tor substituting like apparatus ior selection during said. inspection.

5. ln a system for inspecting electrically operable apparatus connected to and operable over a plurality of lines, said lines being selectable by automatically operable selectors. an automatically operable device tor progressively seizing'said apparatus tor inspection and at. the same time maintaining unrestricted selections of said lines.

6. In a system ior inspecting eiectrically oipierable apparatus connected to and operable over a plurality ot' lines for service connections to other lines, said iirst lines being selectable by automatically operable selectors. an automatically operable device for progresively seizing said apparatus tor inspection and at the same time maintainingja the lines connected to said apparatus selectable for serviceconnections.

7. in a system lor progressively inspecting a plurality of apparatus.vr an auxiliary apparatus? and means auton'iatically operable for replacing the apparatus being inspected by said auxiliary apparatus and for iniee llt)

versely replacing the auxiliary apparatus by the apparatus inspected.

8. In a telephone exchange system, a plurality of automatic switches,`an auxiliary automatic switch, automatially operable means for progressively securing said automatic switches for inspection, for replacing an automatic switch secured for inspection by said auxiliary automatic switch and for inversely replacing the auxiliary automatic switch by the automatic switch inspected.

9. In a telephone exchange system, a plurality of automatic switches for telephone service, an auxiliary automatic switch, autematically operable means for removing an automatic switch from service for inspection and for replacing it by said auxiliary auto matic switch, and automatically operable means tor inversely replacing the auxiliary automatic switch by said automatic switch upon the completion of said inspection.

l0. In a telephone exchange system, automatic switches connected to incoming lines operable over said incoming lines for connection to outgoing lines, an auxiliary automatic switch, means for disconnecting an automatic switch for inspection and for connecting in its place said auxiliary automatic switch, and automatically operable control means for determining the condition ot said automatic switch before it is disconnected.

ll. In a telephone exchange system, a device for testing automatic switches connected to incoming lines Jfor service operation, an auxiliary automat-ie switch, means tor disconnecting an automatic switch from a line and for connecting in its place said auxiliary automat-ic switch, means for inversely disconnecting` the auxiliary automatic switch and connecting in its place said automatic switch upon the completion of said test, and automatically operable control means .tor preventing interference with telephone service connections.

l2. In a telephone exchange system, a device fer testing automatic switches used tor telephone connections, an auxiliary automatic switch, means automatically operable for seizing an automatic switch and replacing it by said auxiliary automatic switch, and means automatically operable to detcrmine whether said switch is busy'in service before making said seizure.

13. In a telephone exchange system, a device ior testing automatic switches connected to incoming lines, an auxiliary automatic switch the same as the automatic switches connected to said lines, and means for disassociating an automatic switch from a line associating said switch with said testing device and associating said auxiliary switch with said line. A

14. In a system for testing automatic switches connected to incoming lines, an auxiliary automatic switch the same as the automatic switch connected to said lines, a testing device, means automatically operable for determining the condition of a switch to be tested, and means automatically operable in response to certain operations of said determining means for disassociating an automatic switch from a line associating saidswitch with said testing device and associating said auxiliary switch with said line.

l5. A system for testing automatic switches in a telephone exchange office connected to two conductor lines incoming from a distant telephone exchange oiiice, an auxiliary automatic switch the same as the automatic switches connected to said lines, a testing` device, means for determining the service condition of a switch to be tested, and means for disassociating the automatic switch to be tested from an incoming line associating said switch with said testing device and associating said auxiliary switch with said incoming line.

In witness whereof, we hereunto subscribe our names this 9th day of August, A. D. 1927.

CARLETON V. TAPLIN. LOUIS M. ALLEN. ARNOLD S. BERTELS. 

